INTERNATIONAL LOW ENRICHED URANIUM FUEL DEVELOPMENT AND NNSA/M3 ROLE PRESENTATION TO THE NATIONAL ACADEMY OF SCIENCE PANEL APRIL 16, 2015 PRESENTED BY: ABDELLATIF YACOUT, MMM EUROPEAN FUEL DEVELOPMENT TECHNICAL LEAD ARGONNE NATIONAL LABORATORY
European High Density LEU Fuel Development High-density U-Mo fuel development is an international effort in cooperation with Russia, Europe (France, Belgium and Germany), and Korea. European Fuel Development is focused on U-Mo dispersion fuel for the RHF, BR2, RJH and ORPHEE reactors; Germany s FRM2 reactor will need the U-Mo monolithic fuel for conversion. Fuel qualification to meet the performance requirements is a challenge just as it is for the USHPRRs. Europe advanced the U-Mo dispersion fuel development through the LEONIDAS program. The program highlighted need for diffusion barriers on the U-Mo powder particles. Belgium s SELENIUM program demonstrated beneficial effects of diffusion barrier coatings on U-Mo powder and highlighted focus areas for further demonstration and fuel performance validation 2 Europe launched the HERACLES program in 2013 and developed a detailed roadmap focused on U-Mo dispersion fuel qualification and EU HPRR conversions. The U.S is a co-sponsor in the HERACLES program RHF JHR ORPHEE BR2 FRM2 2
International Dispersion U-Mo Fuel Qualification Efforts Europe: BR2 (Belgium), RHF and ORPHEE (France) JHR (France) Plans to start with U3Si2 and move to LEU U-Mo fuel in the future as the fuel is qualified Russia: IRT-3M Lead Test Assembly (LEU U-9Mo) were fabricated and will be irradiated in MIR reactor in support of fuel qualification Fuel will be qualified in 2017 Qualified fuel will be used to convert IRT type reactors (IRT-MEPhI, IRT-Tomsk, IR-8), which operate at conditions lower than the EUHFR 3 Korea: KAERI is collaborating with DOE-NNSA/M3 in irradiation testing of LEU U-7Mo KJRR Lead Test Assemblies during 2015 LEU U-7Mo Mini-plates irradiation in HANARO reactor
DOE/EU Collaboration for EU HPRR Conversion Focus in Europe is on the conversions and support for Heracles Initiative on LEU U-Mo Dispersion Fuel Development EU reactors to use LEU fuel: France RHF, ORPHEE, JHR (LEU dispersion fuel) Belgium BR-2 (LEU U-7Mo dispersion fuel) Germany FRM II (LEU U-10Mo monolithic fuel) The US support to the EU (Heracles) Dispersion LEU Fuel Development Provides research on backup (risk mitigation) for the monolithic fuel since dispersion fuel could meet the needs for the conversion of some US-HPRR reactors Provides potential supporting technical data to assist future Russian LEU Dispersion Fuel Development programs 4
5 Historical Background
Research and Test Reactor Fuel Development Timeline Before 1978 6 HEU Fuel U enrichment > 20% 1980s UAlx-Al, UO 2 - Al, U 3 O 8 -Al, and UZrHx 1996- Present LEU Fuel U enrichment < 20%; early types UAlx-Al and U 3 O 8 -Al Qualified U 3 Si 2 - Al with 4.8 gu/ cm 3 and also UZrHx Advanced LEU Fuel 235 U enrichment < 20% U density up to 8-9 gu/cm 3 in dispersion, or ~15 gu/cm 3 monolithic Most promising candidate: U- Mo alloy
Positive Results and Global Interest in U-Mo Fuel U-Mo (7-10 wt.% Mo) dispersion and monolithic fuel forms are being developed for conversion of higher performance research and test reactors. Good irradiation performance of its cubic ϒ-phase. Alloying Mo is to stabilize uranium in the bcc-structured ϒ-phase. High uranium density can be achieved. Fuel testing and out-of-pile programs were initiated worldwide Argentina, Canada, France, Republic of Korea, Russia Dispersion fuel Monolithic fuel 7
Maturity level of Monolithic Vs. Dispersion Dispersion Fuel Performance at bounding conditions remains major issue (BR2 and JHR both very high power + high burnup) Monolithic Base Fuel Performance of Zr co-rolled fuel in US HPRR envelope is considered acceptable Bounding operating conditions of USHPRR do not have high power + high burnup combination Focus on solving fuel performance issues Some fabrication processes must be commercialized, but evolutionary Further understanding of fuel performance at extreme conditions needed Focus on improving fabrication process Base fuel (Zr co-rolled) qualification report to NRC is in progress Fuel performance within USHPRR functional envelope is well understood 8
EUHFR vs. USHPRR Operating Envelope EUHFR have most challenging combination of high burnup and moderate power level. Note that BR2 and RHF designs for LEU assemblies are well-defined and vetted by collaboration between reactor operators and ANL. The CEA and ANL have only recently begun sharing model detail for LEU designs of ORPHEE, and have not yet shared models of JHR. 9
European/US Irradiation Experiments 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 RERTR-1 RERTR-2 RERTR-3 RERTR-4 RERTR-5 RERTR-6 RERTR-10 RERTR-7 RERTR-8 RERTR-9 RERTR-12 RERTR-13 AFIP-1 AFIP-2 AFIP-3 AFIP-4 AFIP-6 AFIP-6 Mk2 AFIP-7 IRIS-1 IRIS-2 FUTURE IRIS-3 IRIS-TUM IRIS-4 E-FUTURE E-FUTURE II Miniplate tests SELENIUM Full-size plate tests Element test LEONIDAS GROUP HERACLES GROUP
11 Fuel Performance
U-Mo/Al Dispersion Fuel U-Mo/Al dispersion fuel elements are plates/rods with U-Mo fuel particles distributed in aluminum matrix. The typical fuel particle size is in average 70 µm. (Y.S. Kim, G.L. Hofman, JNM 419, 2011) 12 (Y.S. Kim, G.L. Hofman, JNM 419, 2011)
Irradiation-Induced Microstructural Changes (Y.S. Kim, et.al, JNM 436, 2013) (YS Kim et al., JNM, 430, 2012) (A. Robinson, INL, 2008) Fission gas bubbles Appear within fuel grains and on grain boundaries Cause fuel phase swelling Interaction layer Form around fuel particles Composition: UMoAlx (amorphous) Degrade fuel meat thermal conductivity Porosity Between the matrix and IL Filled with fission gases Can cause fuel plate failure 13
LEU U-Mo Dispersion Fuel Performance U-Mo is a stable fuel under research reactor conditions Abnormal fuel plate swelling were related to formation of an unstable U-Mo/Al reaction product leading to failure IRIS-2 Gas pocket RERTR-4 Interaction Phase Gas pocket Interaction Phase Aluminum Matrix Aluminum Matrix U-10Mo Powder U-10Mo Powder 14 (F. Huet, RRFM Meeting, 2005) (M.K. Meyer, INL, 2005)
LEU U-Mo Dispersion Fuel Performance U-Mo is only viable solution for the fuel phase due to high density Potential fixes to breakaway swelling Modify the composition of matrix and U-Mo fuel (Si addition) Change the matrix Remove the matrix (Al and Zr clad monolithic fuel) Coated particles to reduce/ eliminate interaction layer Heat treatment to alter grain 15 size and delay breakaway swelling (A. Robinson, INL, 2007) RERTR-8, R9R010 U-Mo magnesium matrix: RERTR-8 R9R010 irradiated to ~ 91% peak 235 U burnup RERTR-7 R2R040 U-7Mo/Al-2Si 69.4% burn-up RERTR-4 V6023M U-10Mo/ Al 80% burn-up (YS Kim, NT 184, 2013) (G.L. Hofman, RERTR Meeting, 200 U-Mo with Si addition (left) and without Si addition (right) under similar operating conditions
Methods for Reducing Interaction Layer Growth! Adding a small Matrix amount Modifications of Si in Al matrix Al matrix Al-2%Si matrix (YS Kim et al., J. Nucl. Mater., 430, 50, 2012) 16 Al-5%Si matrix Al-8%Si matrix Interaction layer progressively reduces with Si concentration in Al.
Methods for Reducing Interaction Layer Growth Coating A. Leenaers, PhD Thesis, UGENT/SCK CEN, 2014 17
Failure Criteria U-Mo/Al-Si, Dispersion Fuel (filled symbols: pillowed and/or large porosity) Burnup (%) 90 68 45 Threshold curve for fuels with Si IRIS-3 RERTR-6 AFIP-1 E-FUTURE IRIS-TUM RERTR-9 RERTR-7 E-FUTURE RIAR KOMO SELENIUM 23 Threshold curve for fuels without Si 0 0 2 4 6 8 Fission rate (1014 fission/cm3-s) 18 (G.L. Hofman, ANL, 2015)
U-Mo fuel swelling behavior - Dispersion fuel (Van den Berghe, JNM 442, 2013) Negligible reaction between the fuel particles and matrix in SELENIUM plates. The fuel swelling is dictated by the solid state swelling due to fission product accumulation. Slower linear growth at the beginning, and acceleration of swelling from 4.5 10 21 f/cm 3. 19
The recrystallization process 20 Recrystallization or grain subdivision is induced by accumulation of irradiation damage. The recrystallization process starts along the preexisting grain boundaries, then moves toward the grain center eventually consuming the entire grain. (Kim et al, JNM 436, 2013)
Recrystallization in U-Mo fuel U-7Mo with Heat Treatment Note significant helpful shift References: [1] Y.S. Kim et al., JNM 436 (2013) 14. [2] A. Leenaers, Sc.D. Dissertation, Univ. of Ghent, Belgium, 2014. [3] Y.S. Kim et al., JNM 454 (2014) 238. [4] Y.S. Kim et al., ANL report, ANL-08/11, 2008. 21 The recrystallized volume fractions were measured using SEM images of atomized U-Mo/Al dispersion fuel. U-Mo fuels show full recrystallization at 4.5-5 10 21 f/cm 3 (U-7Mo w/o heat treatment)
22 EU-US/HERACLES Collaborations Fuel Development and Qualification
European/US Irradiation Experiments 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 RERTR-1 RERTR-2 RERTR-3 RERTR-4 RERTR-5 RERTR-6 RERTR-10 RERTR-7 RERTR-8 RERTR-9 RERTR-12 RERTR-13 AFIP-1 AFIP-2 AFIP-3 AFIP-4 AFIP-6 AFIP-6 Mk2 AFIP-7 IRIS-1 IRIS-2 FUTURE IRIS-3 IRIS-TUM IRIS-4 E-FUTURE E-FUTURE II Miniplate tests SELENIUM Full-size plate tests Element test LEONIDAS GROUP HERACLES GROUP
European High Density LEU Fuel Development Main Components of HERACLES Roadmap Comprehension Phase Industrialization Irradiation Experiments Parallel Activities Modeling Manufacturing Back-end & Cost Assessment Key Dates Comprehension Phase: to 2018 Irradiation experiments and fuel qualification: CY2024-2026 depending on schedule, possible elimination of one experiment, degree of overlap with fabrication scheme. The first qualified use of U-Mo Dispersion fuel would be in BR-2 mid CY2026 to late 2029 Expert Groups (HERACLES/US) Fuel Development Expert Group (FDEG) Fuel Manufacturing Expert Group (FMEG)
European High Density LEU Fuel Development Comprehension Phase Dispersion Fuel SEMPER FIDELIS D M I CS PIE SELENIUM 2 D M I CS PIE E-FUTURE 3 D M I CS PIE MIXED ELEMENT D M I CS PIE FRMII Monolithic Fuel FUTURE-MONO- 1 D M I CS PIE Industrialization FUTURE-MONO- 2 D M I CS PIE MIXED ELEMENT D M I CS PIE CERCA Powder Atomization Development CERCA Powder Coating Development CERCA Dispersed Plates Manufacturing Development CERCA Monolithic Plates Manufacturing Development TUM Mono coating CERCA safety analysis / cost assessment / transport...... BACK-END!
Comprehension Phase Questions What mechanisms lead to: accelerated swelling of UMo fuel alloy at high BU? loss of fuel meat integrity? (e.g., IL growth, interconnected pores)? What mitigations can be applied to address those mechanisms? Hypotheses Completion of fuel recrystallization near ~4.5-5X10 fissions/cc in U7Mo w/o heat treatment: allow gas pores to interconnect & release gas to matrix Possible mitigation!change alloy (e.g., U-7Mo to U-10Mo) or apply heat treatment Interface failure due to weak interaction layer consuming matrix, e.g. : 21 26
Comprehension Phase Activities Activity State of the Art Assessment Objectives Identify and Prioritize Gaps Theory & Data Modeling Phenomenological (particle, IL, microstructure, swelling) Thermo-Mechanical (Plate) Materials Properties Thermodynamics (coating efficacy) Advanced PIE on existing materials (fresh & irradiated ) Fill data gaps Additional samples for clean comparisons (e.g., U10Mo vs U10Mo) Advanced PIE to inform theories (e.g., EPMA or microhardness) Physical Properties Heavy Ion Irradiation UMo Dispersion Feasibility Assessment Design of Subsequent Irradiation Experiments Process and Irradiation Impact on Hardening, Lattice Parameter, Thermal conductivity... Accelerated investigation of irradiation damage and mitigations Assess credibility of fuel system stability for the required operating conditions Design and construct a sub-size plate device Design sample matrix and test conditions
Activity Industrialization Activities Scalable/Reliable Processes Deployable within French Safety Regulations Deployed in stages: Prototype!Pilot!Commercial Industrialization may define requirements of irradiation tests and will constrain it Objectives/Motivation Atomization KAERI process has not yet met French regulatory requirements Rotating electrode should scale in flexible manner Particle Coating Coated Particle Quality Inspection Process with scalability and required coating characteristics not yet defined Coating method not fully defined Also maturity issue for coating of actinide powders Method to measure particle characteristics, coating quality, and homogeneity must be developed Plate Industrialization Mature the high density dispersion plate fabrication process for acceptable yields
Summary Current status of U-Mo fuel development Fuel performance improvements in relation to high power European research reactors have been made particularly by use of coated powder On-going comprehension phase and planned experiments are expected to provide key understanding and additional improvements in fuel performance to achieve fuel qualification goals Existing HERACLES roadmap provides the path for dispersion fuel qualification for conversion of BR2, RHF, JHF, ORPHEE, and a possible monolithic fuel qualification path for FRMII US Colloboration Technical meetings and exchanges with HERACLES group members and participation in experts groups PIE and characterization activities in Europe which are associated with the comprehension phase and fabrication of mini-plates NNSA M 3 activities at US national labs support fuel development and qualification: o Modeling and simulation, experiment data analysis, coating studies, powder heat treatment o EMPIRE experiment will investigate potential variations in fabrication parameters (coating, heat treatment, powder distribution,..) that can provide the needed improvements in fuel performance 29
Irradiation Experiment Must inform/demonstrate: Fundamental fuel system performance (comprehension, predictability) Industrialization selection and maturity Qualification for required irradiation conditions Activity Objectives/Motivation Next Steps Constraints EMPIRE SEMPER FIDELIS SELENIUM II E-FUTURE-III Mini-Plate Test in ATR with alternatives beyond SEMPER-Fi - input from gap analysis Coated Particle Fab Alternatives Compare Powder heat treatment Particle size & distribution Selection Phase. Key HERACLES response to Comprehension Phase 4 full size plates per cycle for 4 cycles Confirm mitigation and predictability of high burnup issues Selection Phase Validation Full-size plates & Final down-select Full-Size Fuel Plate Qualification Down-select fabrication parameters Experiment design and matrix definition Particle coatings Plate fabrications HERACLES defining best set of low and high burnup plates Scope can only be clear after comprehension phase Some fabrication alternatives might not be available by start of irradiation CERCA fabricated plates Coated Particles could be R&D (e.g., KAERI powder with SCK PVD coating) Coated particles by R&D Pilot Scale Fab Mixed Element Fuel System Qualification Curved, constrained plates. Pilot Scale Fab (?)
Status of Comprehension Phase (from FDEG) Based on several meetings of HERACLES/US fuels experts it is confirmed that the two key issues that need to be addressed: High burnup swelling rate of UMo (recrystallization) UMo-matrix interaction layer (IL) formation Mitigation strategies : Swelling (recrystallization) : annealing for Mo homogenization + grain growth (limiting GB) IL formation : Si addition, ZrN coating Models provide acceptable prediction of total swelling Further benchmarking required for qualification Existing correlations for interaction layer formation and fission rate, temperature and time (fission density) can be considered adequate Basis : UMo-Al(Si) irradiations performed in the past. Coating expected to eliminate IL formation KOMO-5 and RERTR-3 data provide support to heat treatment as mitigation for recrystallization Effect on recrystallisation can only be studied by high burnup irradiation, no alternatives Coating: Limited irradiation results available Advanced PIE on SELENIUM samples done and more to be done (FIB samples)
Status of Manufacturing Activities (from FMEG) Powder Atomization: Prototype at CERCA is successful in producing atomized powder using rotating electrode method Electrodes (pins) for atomization have been successfully manufactured at CERCA Powder Coating: PVD coating at SCK and ALD coating at ANL are the two key choices for coating Selection of preferred coating methods and needed tech transfer after irradiation experiments and cost assessments Powder Heat Treatment ANL, INL, SCK CEN have the capability (under development at CERCA/TUM) Heat treatment studies at ANL and SCK show consistent grain growth Further studies to determine heat treatment optimum conditions and Mo homogenization EMPIRE Experiment Manufacturing Most of the plates are to be manufactured by CERCA for irradiation at the ATR Limited plates are to be fabricated by ANL (with varying Mo content) Monolithic plates by TUM/CERCA with C2TWP process will be included in EMPIRE o o Plates with co-rolled Zr coated foil Plates with PVD application of Zr on bare foil Materials Supply and Transfer KAERI powder vs. CERCA powder Logistics of coating and heating treating powder for the experiment at ANL and transfer to CERCA CERCA produced powder inclusion in the experiment? Monolithic foil supply for TUM plates
ANL heat treatment: recent study GB (a) As-atomized U-7Mo powder (Darker lines are GB.) Grain size = 2 6 µm (b) Heat treated U-7Mo at 900 o C for 1 h Grain size = 23 µm Area Mapping of ALD Coated UMo Powder
U-Mo Atomization INL Support Production of U-Mo atomization pins for HERACLES atomization pins were produced for demonstration testing using the TUM atomizer Characterization: DU, alloy, cast-pins, powder Atomizer installed at CERCA 34
Comprehension phase experiments EMPIRE experiment at the ATR SEMPER-FIDELIS at BR2 Key Irradiation Experiments What is expected from the two experiments (from FDEG) Engineering Effect of the heat treatment? o HT delays recrystallization sufficiently to reduce swelling at high BU? Coating or Al-Si? o Eliminate IL formation? Coating required! o Reduction of swelling rate allows fuel system to accommodate IL formation in Al-Si matrix? Cheaper fuel system, better for back-end. Deposition method for coating? o Differences between ALD and PVD? Effect of AlN interlayer? CERCA powder Qualification and modeling Fission rate versus fission density dependences Parameterization of recrystallization (with/without HT) Benchmark effect of variables (kernel size distribution, Mo content, loading, )
European High Density LEU Fuel Development Comprehension Phase Dispersion Fuel SEMPER FIDELIS D M I CS PIE SELENIUM 2 D M I CS PIE E-FUTURE 3 D M I CS PIE MIXED ELEMENT D M I CS PIE FRMII Monolithic Fuel FUTURE-MONO- 1 D M I CS PIE Industrialization FUTURE-MONO- 2 D M I CS PIE MIXED ELEMENT D M I CS PIE CERCA Powder Atomization Development CERCA Powder Coating Development CERCA Dispersed Plates Manufacturing Development CERCA Monolithic Plates Manufacturing Development TUM Mono coating CERCA safety analysis / cost assessment / transport...... BACK-END!
EMPIRE vs. SEMPER-FI (GENERAL) EMPIRE (ATR) SEMPER FIDELIS (BR2) Separate Effects Tests at two complimentary facilities Cross-over testing to better connect existing databases (RERTR, AFIP, E-Future, Selenium) Goal to reach BR-2 target conditions (high power, high burnup) Irradiation of both dispersion and monolithic fuels (TBD for SEMPER FI) Plates have European AG3NE or AlFeNi cladding 37 Mini-plate Scale More variables, more sensitive to scale effect Better variability of power/ Capable of burnup enrichment variation Higher coolant pressure (2 BR2) PIE at MFC (split the workload) Unique (complementary) PIE capabilities: FIB (key to coating studies) Sub-size or Full (TBD) - Fewer variables, more prototypic for full size Limited variability of power/ burnup, current peak is 470 W/ cm 2 Lower coolant pressure PIE at LHMA (split the workload) Unique (complementary) PIE capability: EPMA (TEM for fuel, not coating)
EMPIRE vs. SEMPER-FI (MATRIX) EMPIRE (ATR) SEMPER FIDELIS (BR2) Major focus on role of coatings, with/without heat treatment Coating application method: PVD vs ALD Type of coating: ZrN vs ZrN/AlN Mo content: U-10Mo (> 5 U) Major focus on role of heat treatment at distinct fission rate vs. fission density ZrN/PVD coating: with and without heat treatment to high burnup (beyond SELENIUM) Heat treatment of U-7Mo: with and without! single optimised procedure Variable fission rate and burnup Al-Si Matrix (with heat treatment) U-7Mo particle size distribution: standard and modified 38 KAERI and CERCA powder Plates made by CERCA and ANL Earlier insertion, September 2016: Data for comprehension phase available earlier Monolithic: C2TWP, co-rolled & PVD Coated) CERCA powder Plates made by CERCA Later insertion, second half 2016, after EMPIRE: Data for comprehension phase available later
39 Specific US Activities
E-FUTURE and SELENIUM PIE Support US Dispersion Fuel Activities in Support of HERACLES Comprehension Phase Microsctructural Characterization Fabrication Support EMPIRE Experiment Analysis and interpretation of test data Comparison with other relevant test results. Support of cutting plans and samples selections Characterization of Fabricated plates & archive samples Coating structure Thermal properties Ion irradiation experiments Alternate coating activities in the US (e.g., ALD) Ion irradiation (test coating) Support EMPIRE fabrication needs Fabrication and atomization studies Experiment Design and Analysis and matrix definition Conceptual design based on output from working groups Fabricate materials/plates as needed Dispersion Fuel Modeling and Simulation Dispersion Fuel Modeling and Simulation 40 DART code mechanistic modeling Modeling of fundamental U-Mo fuel properties CFD Simulation of SELENIUM experiment and EMPIRE support ABAQUS/Multiphysics models of full size plates Modeling of coating-fuel and coating- matrix interactions Dispersion Fuel Plates Modeling
Burnup (%) 90 68 45 Failure Criteria U-Mo/Al, Dispersion Fuel (filled symbols: pillowed and/or large porosity) IRIS-1 IRIS-2 IRIS-TUM RERTR-2 RERTR-3 RERTR-6 RERTR-6 RERTR-5 RERTR-5 FUTURE 23 Threshold curve for fuels without Si 0 0 1.8 3.5 5.3 7 Fission rate (1014 fission/cm3-s) 41 (G.L. Hofman, ANL, 2015)
How the acceleration of fuel swelling occurs? - Increased fission gas bubble swelling during fuel recrystallization Fuel swelling vs. Fission density (SELENIUM and E-FUTURE plates) Fission gas bubble swelling vs. Fission density 40 30 U-10Mo (atomized) U-10Mo (monolithic-rertr12) U-9Mo (K004) U-9Mo (RIAR) U-7Mo (IRIS-1) (ΔV/V0)g (%) 20 10 42 (Van den Berghe, JNM 442, 2013) 0 (G.L. Hofman, ANL, 2015) 0 2 4 6 8 Fission density (1021 fissions/cm3)
Increased gas bubble swelling during recrystallization Subdivision of fuel grains results in an increased number of grain boundaries and triple points where large intergranular gas bubbles nucleate. Reduction of fuel grain size results in shortened gas atom diffusion distance from the center of a fuel grain to its boundary, which accelerates intergranular bubble growth. These changes lead to a significant increase of gas bubble swelling.
U-Mo fuel recrystallization kinetics 0.6 0.1 U10Mo-dispersion U7Mo-dispersion U7Mo-dispersion-annealed log(-ln(1-vrx)) -0.4 U9Mo-Russian -0.9-1.4 0 0.2 0.4 0.6 0.8 log(fd) Fuel material U-7Mo U-10Mo U-7Mo Incubation FD (10 21 f/ 1.86 2.5 (annealed) 3.0 cm The recrystallization ) kinetics is a function of burnup (JMAK plot). Mo content and initial grain size are important factors impacting the recrystallization kinetics. 44